In recent years, a resistive rewritable non-volatile switching element whose ON and OFF states can be rewritten in accordance with a resistive state (hereinafter referred to also as a resistive switching element) has been developed (see Patent Literature 1).
FIGS. 13A to 13C are diagrams for explaining such a resistive rewritable non-volatile switching element. As shown in FIG. 13A, a resistive switching element 101 is structured by an anode 110 being a first electrode, a cathode 112 being a second electrode, and an ionic conductor 111 interposed between the anode 110 and the cathode 112.
The anode 110 is an electrode that supplies metallic ions to the ionic conductor 111, and is chiefly made of copper and others. The cathode 112 is an electrode that does not supply metallic ions to the ionic conductor 111, and platinum or the like is used therefor. The ionic conductor 111 has a characteristic of allowing the metallic ions supplied from the anode 110 to move, and tantalum oxide or the like is used therefor.
FIG. 13B shows the case where the resistive switching element 101 is in the ON state, that is, the state where electrical conduction is established across the opposite electrodes. By applying a programming voltage Von to the anode 110 and applying a ground voltage (hereinafter referred to also as the ground voltage) Vgnd to the cathode 112, the resistive switching element 101 can be set to the ON state.
FIG. 13C shows the case where the resistive switching element 101 is in the OFF state, that is, the state where the opposite electrodes are electrically disconnected from each other. By applying the ground voltage Vgnd to the anode 110 and applying a programming voltage Voff to the cathode 112, the resistive switching element 101 can be set to the OFF state.
Such a process of setting the resistive switching element 101 to the ON state or the OFF state is referred to as programming. Further, the voltage applied to the resistive switching element 101 when the programming is performed is referred to as the programming voltage. Note that the ON state and OFF state of the resistive switching element 101 are retained even when the power supply is shut down.
Further, Patent Literature 2 discloses a reconfigurable circuit using such resistive switching elements. The reconfigurable circuit disclosed in Patent Literature 2 has a programmable cell array, and the programmable cells have function blocks and programmable interconnects. The function blocks are circuits that realize various logical operation functions in accordance with any program. Further, the programmable interconnects are each an interconnect connecting between the function blocks in accordance with any program. Patent Literature 2 discloses an example in which such resistive rewritable non-volatile switching elements are used as elements realizing the programmability.
With the reconfigurable circuit disclosed in Patent Literature 2, a circuit can be reconfigured by applying the programming voltage to each of the resistive switching elements structuring the reconfigurable circuit, to switch the ON state and OFF state of the resistive switching elements to the desired state.